Commit 26a2dfde authored Jun 18, 2013 by Xiang Wang Committed by Vinod Koul Aug 05, 2013

dma: mmp_pdma: clear DRCMR when free a phy channel



In mmp pdma, phy channels are allocated/freed dynamically.
The mapping from DMA request to DMA channel number in DRCMR
should be cleared when a phy channel is freed. Otherwise
conflicts will happen when:
1. A is using channel 2 and free it after finished, but A
still maps to channel 2 in DRCMR of A.
2. Now another one B gets channel 2. So B maps to channel 2
too in DRCMR of B.
In the datasheet, it is described that "Do not map two active
requests to the same channel since it produces unpredictable
results" and we can observe that during test.

Signed-off-by: Xiang Wang <wangx@marvell.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

parent 027f28b7

drivers/dma/mmp_pdma.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -252,10 +252,16 @@ static void mmp_pdma_free_phy(struct mmp_pdma_chan *pchan)
		{
		struct mmp_pdma_device *pdev = to_mmp_pdma_dev(pchan->chan.device);
		unsigned long flags;
		u32 reg;

		if (!pchan->phy)
		return;

		/* clear the channel mapping in DRCMR */
		reg = pchan->phy->vchan->drcmr;
		reg = ((reg < 64) ? 0x0100 : 0x1100) + ((reg & 0x3f) << 2);
		writel(0, pchan->phy->base + reg);

		spin_lock_irqsave(&pdev->phy_lock, flags);
		pchan->phy->vchan = NULL;
		pchan->phy = NULL;

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